Pressure sensing and responding device

ABSTRACT

A device is disclosed which includes in combination a pressure sensing valve and a linking mechanism responsive thereto. The pressure sensing valve includes a housing adapted at one end for connection to a pressurized engine coolant system. The same end of the housing also contains a flexible diaphragm which divides that end of the housing into two chambers. The other end of the housing is cylindrically bored to accommodate a slidable spring biased porous piston. A diaphragm face plate, in contact with the flexible diaphragm, is adjustably mounted to the slidable piston such that as the diaphragm is expanded, the piston is slidably moved within the bored or cylinder portion of the housing. Movement of the piston exposes and/or blocks a combination of ports opening into the cylindrical bore. The outlet end of one of the ports leads to a sump while another outlet leads to a pressurized liquid carrying line connected to a linking mechanism positioned between the fuel injector&#39;&#39;s governor and the foot throttle control. Port selection is controlled by the location of the piston within the housing. The piston within the housing is actuated by a positive pressure exerted on the flexible diaphragm by the heated coolant.

United States Patent Williams May 13, 1975 PRESSURE SENSING ANDRESPONDING [57] ABSTRACT DEVICE A device is disclosed which includes incombination a [76] Inventor: Horace A. Williams, 6123 Rodeo presslfreSensing valve and a linkillg t Ln Salt Lake City, Utah 84121 sponsivethereto. The pressure sensmg valve includes a housing adapted at one endfor connection to a pres- Filed: June 4, 1973 surized engine coolantsystem. The same end of the [211 App]. NOJ 366,450 housing also containsa flexible diaphragm which divides that end of the housing mto twochambers. The other end of the housing is cylindrically bored to ac-[52] US. Cl. 137/625.34; 251/613; 251/368 commodate a slidable Springbiased porous piston. A [51] Int. Cl. Fl6k 11/07; Fl6k 51/00 diaphragmface plate, in Contact with the flexible i [58] Field of Search 251/613,368; 137/269, phragm is adjustably mounted to the slidable piston137/625-33 62534 625-37 such that as the diaphragm is expanded, thepiston is slidably moved within the bored or cylinder portion ofReferences C'ted the housing. Movement of the piston exposes and/orUNITED STATES PATENTS blocks a combination of ports opening into thecylin- 347915 8/l886 Blackburn 251/368 x drical bore- The Outlet end ofone Of the ports leads to 2,493,449 1/1950 Fitch .3 X a sump whileanother outlet leads to a pressurized liq- 2,868,483 1/1959 Krueger.....3 X uid carrying line connected to a linking mechanism 3,070,12412/1962 Fitzpatrick l37/625.34 X positioned between the fuel injectorsgovernor and 3,363,412 1/1968 Fischer et a]. 251/613 X the foot throttlecontrol. p Selection is controlled 3,406,702 l0/l968 Jenney l37/625.34 Xy the location of the piston within the housing. The 3,466,950 9/1969Mummert 137/6253? X Primary Examinerl-Ienry T. Klinksiek Attorney,Agent, or FirmRichard F. Bojanowski piston within the housing isactuated by a positive pressure exerted on the flexible diaphragm by theheated coolant.

12 Claims, 8 Drawing Figures PATENTEBHAYIBISYS 3.882.900

sum 30$ 4 PATENIED M 1 1 1 3; 882.90 0

SBEEI t Of 4 {/8 m :SUMP 74 7 v- |75& I44 l43 SUMP on. PUMP 34 GOVENORFOOT THROTTLE we I00 LINKAGE COOLANT PRESSURE Y on. SUMP FIG. 7

lBZ

OIL PUMP 1 -COOLANT PRESSURE SUMP lF/G. 8

1 PRESSURE SENSING AND RESPONDING DEVICE BACKGROUND OF THE INVENTION 1.Field of the Invention This invention is directed to a pressure sensingand responsive device for controlling the amount of fuel introduced intoan internal combustion engine and particularly to a pressure-type valveresponsive to pressure changes of an internal combustion engine'scoolant and an extendible linking mechanism actuatable by saidpressure-type valve.

2. State of the Art All diesel engines are equipped with pressurizedlubrication and coolant systems. The former supplies oil to all mainconnecting rods and cam shaft bearings as well as to other movingpartswithin the engine. In operation a gear type pump is normally used todraw oil from the sump or oil pan through an intake screen and oilfilter and finally on to an oil cooler. From the oil cooler, the oilflows through passageways that connect oil galleries in the cylinderblock and cylinder heads for distribution to the bearing and rocker armmechanisms as well as to other functional parts of the engine.

I The coolant used in the engine coolant system is normally circulatedthrough the engine by a centrifugaltype pump. Heat is removed from thecoolant by a heat exchanger or radiator. Flow of the coolant through theradiator is controlled by a valve actuated by a thermostat. Although thethermostat is capable of restricting flow of the coolant during theperiod when the engine is heating up, the thermostat cannot prevent theengine from overheating when adverse operating conditions or amalfunction occur. To advise the vehicles operator of an impendingmalfunction in the engines cooling or lubrication systems, all enginesare equipped with gauges, lights and other signaling and/or warningdevices.

Generally, these signaling or warning devices comprise atemperature-sensing means, such as a thermocouple; which measures andreports the engines coolant and oil temperatures at a particular pointin the system. If a malfunction occurs, the reported temperature is, inmost cases, many degrees above or below the actual temperature. This lagin temperature reporting can cause serious damage to the vehiclesengine.

In addition to warning devices, the vehicle is also normally equippedwith instruments to advise the operator of existing engine conditionsprior to start up. Unfortunately though, a large percentage of theoperators will pay little attention to these instruments and willoperate an engine, such as a diesel, at full capacity before the enginecoolant temperature and oil pressure reach proper operating levels. Thistype of use produces an unnecessary strain on the engine, inefficientburning of the engines fuel and the emission of excessive amounts ofblack exhaust which contributes to the pollution of the atmosphere inthe form of unburnt hydrocarbons and nitrogen oxide.

Normally a diesel is also provided with an electrical alarm system inconjunction with an electrical engine shutdown system. If an abnormalcondition occurs, the engine will be automatically shut down and analarm bell will be sounded to advise the operator of an existingmalfunction.

In addition to electrical systems, various mechanical shutdownsystemshave also been proposed. In each instance, though, the system isactuated by an electrical switch which is activated by a change in thevehicles oil pressure, fuel pressure and/or coolant temperature.

Systems of the type above described have generally been unsatisfactoryas they are for the most part unreliable, are easily overridden and arecostly to install and maintain. Another problem has been that it isgenerally unsatisfactory to have a complete and unexpected engineshutdown as the operator may find himself in a precarious situationwhich could be further compounded if the engine was totally shut down atthat particular time. Automatic shutdown systems on diesels areespecially dangerous when the vehicle is traveling over. mountainousterrain or on an interstate highway where violations of minimumoperating speeds could be perilous to not only the operator but also toothers traveling the interstate.

In addition to the systems above described, the diesel engines are alsoequipped with some type of governor for automatically varying the amountof fuel injected into the engine cylinder whenever fluctuations in loadand/or changes in operating terrain are encountered. Generally thegovernor is part of themechanical linkage connecting the foot throttlewith the fuel injectors. The purpose of the governor is to maintain anear constant engine speed under normal operating conditions and therebyminimize excessive engine strain.

OBJECTS OF THE INVENTION It is therefore an object of this invention toprovide a pressure sensing and responsive system which avoids thedisadvantages and problems aforementioned.

Another object is to provide a type of fail-safe device and system whichis capable of responding to changes in oil and coolant pressureswhenever a pressure line malfunction occurs which would have an adverseaffect upon the vehicles operation.

Another object is to provide a device which is capable of providing arapid response to an increase or loss in oil and/or coolant pressure.

Still another object of this invention is to provide a sensing systemwhich not only advises the operator of malfunctions but also isconducive to optimizing fuel consumption and thereby reducing, if notovercoming, excessive emissions of contaminants from the engines stacks.

Another object is to provide a system which is capable of reducingvehicle speed whenever a malfunction is detected in the lubrication orcoolant systems.

Another object is to provide a device which prevents operation of thevehicle during startup until such time that the vehicles recommendedoperating coolant temperatures and oil pressures are attained.

Still another object of this invention is to provide a system forrapidly detecting changes in temperature of an engines coolant bysensing the coolants corresponding change in pressure.

SUMMARY OF THE INVENTION These and other objects and advantages areachieved by the pressure sensing and responding device which comprisesan engine coolant pressure sensing means and a means for transmitting asignal, in response to the coolant pressure, to a pressure responsivelinking means which automatically alters the amount of fuel introducedinto an internal combustion engine.

More specifically, the device of this invention includes a pressureresponsive valve comprising a housing having a slidable porous pistoncarried in one end thereof. The other end of the housing contains infixed position a flexible diaphragm which divides the housing into twopressure chambers. When a pressure change occurs in one of the chambers,the diaphragm is expanded and the piston, which is connectably attachedto the diaphragm is slidably moved. As the piston moves, various portsare simultaneously blocked and- /or exposed to permit a pneumaticpressure signal to be transmitted to a pressure responsive, extendiblelinking means positioned intermediate the fuel injection systemsgovernor and foot throttle control. When the pressure signal falls belowa preselected minimum, the amount of fuel injected into the engine isreduced by an automatic shortening or lengthening of the pressureresponsive linking means. Preferably the pneumatic pressure signal is abranch of the engines closed pressurized oil lubrication circuit. Withthis system any malfunction occurring in the engines pressurized coolantor lubrication systems will be detected and will automatically reducethe amount of fuel introduced into the engine, causing a reduction inengine speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross section of thepressure responsive valveof this invention.

FIG. 2 isan exploded view of the pressure responsive valve shown in FIG.1.

FIG. 3 is a side cross section of a pressure responding linkingmechanism.

FIG. 4 is an exploded view of the linking mechanism shown in FIG. 3.

FIG. 5 is an isometric view of a linking mechanism which is installedinternally and is normally submerged in oil.

FIG. 6 is an exploded view of the linking mechanism shown in FIG. 5 withportions shown in cross section.

FIG. 7 is a schematic showing the working relationship between thepressure responsive valve of FIGS. 1 and 2 and the linking mechanismshown in FIGS. 3 and 4.

FIG. 8 is a schematic showing the working relationship between thepressure responsive valve of FIGS. 1 and 2 and the linking mechanismshown in FIGS. 5 and 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, thepressure responsive valve 10 includes a bell-shaped housing 12 and alower housing member 16. A diaphragm 18 extends between the two housingsand is held in position by bolts 20 passing through threaded openings inthe peripheral lips 24 and 26 which extend outward from the housings 12and 16.

The extended diaphragm l8 separates the two housings to form a pressurechamber 28 and a breathing chamber 30. The latter is maintained atambient pressure by a breather opening 32. The lower housing 16 isprovided with a threaded opening 34 for receiving a threaded nipple (notshown) for directing an engines pressurized coolant into the pressurechamber 28. A centrally bored stop member 40, having spaced-apart ports42, is positioned over the outlet end 36 of opening 34 and directs thepressurized coolant into the pressurized chamber 28 via a centralopening 41 in communication with outlet ports 42. The other end of thestop member has a threaded shaft 43 extending outwardly therefrom andthrough an annular opening in the diaphragm 18. Within the breathingchamber 30, the diaphragm 18 is in contact'with an annular plate 44having a central opening through which the threaded shaft 43 passes. Anadjusting nut 48, fitted over the threaded shaft 43, holds the annularplate 44 flush against the diaphragm 18.

A porousvpiston member 50 having its end sections SOaand 50b separatedby an annular groove or space 52 is slidably carried within the cylindersection 54 of the bell-shaped housing 12. One end of the piston member50 also contains a threaded opening 56 which engages the threaded shaft43 of stop member 40 and held in locked position thereon by a threadedlocking nut 62. The end sections 50a and 50b of the porous piston arefitted with O rings 58 and 60 for sealing against the cylinders innerwall. The end face of the porous piston 50 is adapted with a boredportion 64 to receive a coil spring 66 which continuously urges thepiston toward and against the inner wall of the lower housing member 16.The compression of the spring is regulated bya threaded plug 68 fittedin the threaded end of the cylinder 54. To assist in turning the plug, alateral slot 69 is provided. A locking nut 70 fits over the threadedplug 68 locking the plug in position after the desired springcompression has been achieved.

The outside wall 72 of the cylinder section of the bell housing 12contains a threaded liquid inlet opening 74 fitted with an adapter 76which in turn is connected to a line leading to the engines oil pump(FIGS. 7 and .8). On the other side of the cylinders outlet wall athreaded liquid outlet opening 78 is provided which also is fitted withan adapter 80 connected to a line line leading either to sump or to thelinking mechanism as depicted in FIGS. 7 and 8. The inlet opening 74intersects a longitudinal channel 82 bored into the cylinder wall of thehousing. A first transverse intersecting channel 84 is provided andconnects the longitudinal 82 channel with the cylinder section 54 toprovide an interconnectirig passageway between the cylinder and thelongitudinal channel. A second transverse intersecting channel 86positioned apart and parallel to the first transverse intersectingchannel 84 connects the cylinder with the longitudinal channel 82. Thedistance between the two transverse intersecting channels is slightlyless than the height of the pistons end section 50a.

Bored outlet opening 78 passes partially through the cylinder wall andintersects a second longitudinal channel 88 and, like the firstlongitudinal channel 82, has two transverse intersecting channels 90 and92 which connect the cylinder section 54 with the longitudinal channel88. lntersecting channels 86 and 92 are positioned opposite each otherso that both channels are either exposed or blocked at the same timedepending on the position of the piston 50 within the cylinder section54. lntersecting channels 84 and 90 are positioned such that when thediaphragm is relaxed, i.e., at ambient pressure, both channels open intothe annular groove 52 permitting a direct flow of pressurized oil fromthe inlet 76 to the outlet 78 which leads to sump. In some cases,depending on the design of the linking mechanism and/or the use of thepressure sensing valve, the outlet 78 may lead elsewhere than sump.

At or near the end of thebell-shaped housing 12, another outlet channel94 is provided which connects with the longitudinal channel 82. A line96 connects channel 94 with one of the linking mechanisms shown in FIGS.3 through 6 interposed'bet'ween the governor ,of the engines fuelinjection system and the engines throttle. In cases where the pressuresensing valve is connected to a linking mechanism that is mounted withinthe engine (FIGS. 5 and 6), channel 94 is normally closed and outlet 78is connected directly'to the linking mechanism. A more thoroughdiscussion of the various types of linking mechanisms and theirapplications will subsequently follow.

An important feature of this invention is that the pistons be porous.That is, the piston must contain pores of such size and diameter that aportion of the pressurized lubricating oil passes into the piston spores and is retained therein. It has been found that when a nonporouspiston or one which is not capable of selflubrication is used, pistonsidelocking and/or scoring are more likely to occur. 1 In FIGS. 3 and 4,an extendible linking mechanism is depicted for automatically alteringthe amount of fuel that can be introduced into an engines cylinder. Thelinking mechanism is inserted as part of the linkage connecting thegovernor and the throttle control systern. Since the linking mechanismis extendible in length it is capable of automatically adjusting thelinkage between the governor and the throttle control in direct responseto changes in coolant and/or oil pressure. In essence, therefore, thelinking mechanism can be described as being an extendible mechanicallinkage responsive to direct or indirect changes in pressure. Forpurposes of this invention, the terms .mechanical linking means orextendible linking mechanism are understood to mean a mechanical devicefor automatically varying the length of the linkage between the governorand the throttle control in response to a change in pressure of acontrol fluid, such as oil, from the engines lubrication system. In someareas, extendible linking mechanisms are referred to as a robe.

In addition, the linking mechanism canbe adapted so that it can be usedin either a wet or dry system. If the linking mechanism is'used'in a wetsystem, it is normally enclosed in a housing and is contained within alubricating fluid. Such a linking mechanism is shown in FIGS. 5 and 6and is normally used on diesels manufactured by companies such asCaterpillar Tractor Co.

When the linking mechanism is adapted for use in a dry system, thelinking mechanism is externally located and is not submerged in alubricating fluid-Such linking mechanisms would be used on dieselsmanufactured by" such companies as Cummins, DetroitDieseI or ingasoline-type automotive engines such as those produced by GeneralMotors, Ford or Chrysler Corporations. One embodiment of a drymechanical linkage is shown in FIGS. 3 and 4.

As shown in- FIGS. 3 and 4, the extendible linking mechanism 100includes a housing 101 formed by abutting the base sections of twoidentical bell-shaped members 102 and 104 respectively. The bell membersare separated by a distribution disc 106 containing ,an annular groove108 cut into both-facesvofthe disc. A bored vertical channel 110 extendsdownward from .the edge of the disc and intersectsboth of theannulargrooves 108 by means of a horizontal channel l11-to provide anintersecting passagewayfor {thedistribution threaded ..c ap or bolt 109Centrally and inwardly from v .the annularl' groove leach face of.theidisc contains a concave indentatibn lll flexible Neoprene dia-'tion disc, theNeoprene diaphragms and the peripheral Joutward-extending flanges 12 0 and 122 of the bell housings 102 and l04respectively.

The outer end of each bell membercontains an opening 1j24 and. 126 forreceiving a slidable rod 128 and I 130 havinga'convex-shaped head 132and 134 which 7 matches a curvatu rethe concave indentation carried bythedistributiondisc 10 6. The convex heads 132 and 134 are continuallyurged into the concave indentations 112 by means of a coil spring 136and 138 seated against a shoulder 140 formed within each of the bellmembers 102 and 104. The rods are held in a fixed position by lockingnuts 141 and 143. As shown, the tension on the spring is sufficient tourge the flexible diaphragm into the concave indentation. The peripheralflanged ends and 122 of the bell members contain horizontally boredconstricted channels 142 which intersect with vertical channel 110. Theconstrictions in channels 142 permit the pressurized oil to enter orexit the vertical channel at a predetermined controlled rate. Theseconstrictions are such that a convenient time delay is built into thelinkage system. This prevents the feeding of excessive amounts of fuelinto the engine during acceleration and thereby avoids flooding- ITheconstricted horizontal channels 142- arefitted with adapters 144which in turn are connected to a tubular line 143. The tubular lines arejoined to'a pressurized oil system (see FIGS. 7 and 8) so that a portionof the pressurized oil will flow through the linesand into the verticalchannel for distribution into the annular grooves formed on both facesof the distribution disc 106. As the oilpressure is gradually increased,the flexible diaphragms are urged outwardly forcing the springloadedrods outwardly and away from each other. The ends of each rod 128 andare threaded to facilitate connecting the linking mechanism between thegovernor and the throttle control.

As long as the pressure of the coolant is betweenfor example 4 and 18psi, and preferably between 7.and 15 psi, the mechanical linkagebetweenthe governor and the throttle control is relaxed as is shown in FIGS. 3and 4.-In the relaxed position the linkage between the governor andthrottle control is capable of being extended by as much as one-quarterof an inch. With the linking mechanism in its extended position, thefuel injection system functions in a normal manner, that is, fullpoweris available to the operator. However, with the linking mechanism in arelaxed position, the operator is able to obtain an enginespeedapproximating only a fast idle even if the accelerator is fullydepressed. Thisof course prevents operation of the diesel untilmanufacturer-recommended operating pressures and temperatures arereached.

1 The mechanical linkage shown generally in FIGS.

Sand 6 by numeral comprisesv a housing 152 having a link rod 153connected to and extending outward therefrom. An opening 154 is providedin the end of thelink rod forinterconnecting with the'linkage be-,tweenthe governor and the throttle 'controlof a diesel .engine. Theinner portion of the housingis bored to ac- ,cornmodate aporouspiston-155. Extending outward from the piston is a rod 156 having anopening 157 in its outer end. A coil spring 158 encircles the rod and isheld under compression within the housing by bushing 159 and a snap ring161.

Housing 152 also includes internally threaded openings 162 and 163 towhich pressurized oil lines are connected. Restricted port 164 andpartially restricted port 165 are also provided to return the oilintroduced into the housing through the openings 162 and 163 to sump.Since restricted port 165 is larger than port 164, the pressurized oilexiting through port 165 exits at a rate faster than through port 164.Since the oil exiting through port 164 moves at a slower rate thanthrough port 165, a back pressure is created which is sufficient toovercome the tension of coil spring 158.

The housing also contains a chamber 170 separated from the pistonscylinder 171 by a shoulder 172. An O-ring 173 is carried along theperipheral edge of the piston to create a floating environment for thepiston within the housing and to separate the two oil chambers one fromthe other. In addition ports 162 and 163 are sufficiently constricted tocreate a time delay which prevents excessive amounts of fuel from beingintroduced into the engine during acceleration. Operationally, thepressure sensing valve 10 is connected to the extendible linkingmechanism either 100 or 150 by a seriesof lines as shown in theschematics of FIGS. 7

and 8.

In FIG. 7, the pressure sensing valve is connected to an external or drylinking mechanism by a pressurized oil line 175. Pressurized oil entersliquid inlet 74 through line 176 and, depending on the position ofpiston 50 within the cylinder 54, passes to either line 175 or line 177leading to sump. Pressurized coolant enters the pressure sensing valvethrough inlet 34 via line 178.

Prior to engine startup, the porous piston 50 is in a relaxed positionas shown in FIG. 1. In this relaxed position, intersecting channels 84and 90 are open permitting the pressurized oil to enter through inlet 76and pass into the annular space 52 located between the pistons endsections 50a and 50b. The oil then flows into intersecting channel 90and longitudinal channel 88 and out through the liquid outlet 78 tosump.

As the engine warms up and the coolant is heated, a positive pressure isexerted by the coolant on diaphragm 18 forcing the spring-loaded pistonto move toward the end of the cylinder and against spring 66 closingchannel 90. Channels 89 and 90 remain closed at normal operating coolanttemperatures and pressures. Under normal operating conditions the oil isrerouted into the longitudinal channel 82 and out through intersectingchannel 94 and line 96 to the linking mechanism shown in FIG. 3. At apredetermined coolant pressure (determined by the coolants temperature),the linking mechanism will become extended and will permit the fuelinjection system to operate in. a normal fashion. However, if thecoolant temperature increases or decreases above or below normal, thepiston is repositioned within the cylinder and the pressurized oil isrerouted through other channels bored in the valve. If, for example, thetemperature of the coolant rises above normal operating temperatures sothat a greater pressure is exerted on the diaphragm, the piston 50 willcompress the spring 66 still further and uncover intersecting channels86 and 92. This will then direct the oil once again to sump via channel92 and concomitantly therewith gravitationally drain the pressurized oilfrom the linking mechanism through channels 94 and 86, releasing thepressure thereon. When the oil pressure on the linking mechanism isreleased, it will automatically retract and thereby reduce the amount offuel introduced into the engine, slowing the engine speed to thatapproximating a fast idle. I

When the engine is shut down and the coolant temperature approachesambient temperature, the piston retreats, opening and closing ports inreverse manner until the piston returns to the position shown in FIG. 1.

When the pressure sensing valve 10 is connected to a wet or internallinking mechanism 150 (FIGS. 5 and 6) as shown in FIG. 8, the pressuresensing valve is somewhat modified. As shown, the outlet 94 is cappedand line 180 leads from outlet 78 to the linking mechanism 150 ratherthan to sump as shown in FIG. 7. The coolant enters the pressure sensingvalve through opening 34 and line .181 while the pressurized oil entersinlet 74 through.line 182.

A second pressurized oil line 183 continuously carries pressurized oilto the linking mechanism through inlet 163. Since the linking mechanismis carried within a sump housing filled with oil, the oil passes throughconstricted openings 164 and 165 to sump.

Prior to engine start up, piston 155 is being urged by spring 158against shoulder 172 located within cylinder 170. In this position fullthrottle is available to the operator for startup. Almost immediatelyafter startup or as soon as the oil pump has built up a preselected oilpressure sufficient to overcome the tension of spring 158, the piston155 is slidably moved within the cylinder 17] extending rod 156 When thelinking mechanism is in the extended position, the operator is unable toaccelerate beyond a fast idle.

As the engine warms up and the coolant reaches a temperature of betweenF and F, a sufficient pressure is exerted on the diaphragm 18 of thepressure sensing valve 10 forcing the spring loaded piston to moveagainst the spring 66 closing channel 90. When this occurs, -the oilpassing to the linking mechanism 150 through line 180 is blocked and theoil in chamber 170 of the linking mechanism is slowly drained to sumpthrough constricted opening 164. As the pressure in chamber 170 isreduced the piston is slowly moved toward the shoulder 172 by spring 158and by the pressurized oil entering the cylinder 171 through inlet 163.Since openings 164 and 165 are constricted a built in throttle delay ortime delay is provided which retards full fuel injection when the engineis accelerated. This aids in reducing acceleration exhaust smoke andhelps to improve fuel economy.

It should be noted that constriction 165 is somewhat larger thanconstriction 164 and thus permits a sufficiently high oil back pressureto build up in chamber to overcome the spring 158 and the oil backpressure in cylinder 171. This occurs on startup and if the enginescoolant temperature exceeds a preselected maximum. When the coolanttemperature rises above the normal operating range so that a higherpressure is exerted on the diaphragm 18, the piston 50 will compress thespring 66 still further and uncover channels 86 and 92. This will thenopen line permitting oil to enter chamber 170 forcing the piston 155 toslidably move outward extending the linking mechanism 150 in the samemanner it did on startup. When this occurs, the speed of the engine isreduced to that of a fast idle,

preventing the operator from operating the vehicle at high speeds whenthe engine is overheating.

If desired, the linking mechanism may be adapted with an overridingsystem which is capable of overriding the pressure sensing valve. Thiscan be conveniently accomplished by attaching an operator-actuatablepressurized fluid line to the linking mechanism which, when actuated,will force the piston in a direction which will provide immediate fullfuel injection.

Although the inventive concept described herein refers to specificfeatures, such specificity is intended forexample only and is not to beconstrued as limiting this invention as it is intended that theinvention be limited only by the claims appended hereto. It is alsoevident that certain changes, modifications and variations could bereadily made without departing from the spirit and scope of thisinvention.

I claim:

1. A pressure sensing valve comprising a'valve housing, a pressuresensing means carried within said housing, a porous valve meansresponsive to said pressure sensing means and a series of portsconnected to fluid carrying passageways bored within said housing, saidports being exposed or covered by said valve means as pressure changesare sensed by said pressure sensing sending means.

2. The valving device of claim 1 wherein the valve means comprises aporous piston slidably carried within said housing.

3. The valve device of claim 2 wherein said piston is continually urgedtowards and in contact with said pressure sensing means.

4. The valving device of claim 3 wherein said porous piston iscontinuously urged toward said pressure sensing means by a springbiasing means.

5. The valving device of claim 1 wherein the pressure sensing meansincludes a pair of pressure chambers separated by a flexible diaphragm.

6. The valving device of claim 5 wherein one of said pressure chambersis maintained at ambient pressure.

7. The valving device of claim 5 wherein said pressure chamber ismaintained at ambient pressure and the other pressure chamber is adaptedto accept pressures greater than ambient.

8. The valving device of claim 1 wherein said valve means comprises aporous piston slidably carried within said housing and said sensingmeans includes a pair of pressure chambers separated by a flexiblediaphragm.

9. The valving device of claim 8 wherein said porous piston is beingcontinually urged against said diaphragm by a spring biasing means.

10. The valving device of claim 9 wherein said porous piston has anintermediate cross sectional area less than the cross sectional area ofeach of its ends.

11. The valving device of claim 8 wherein the compression of said springbiasing means is capable of being varied by an adjustable means.

12. The valving device of claim 1 wherein one of said pressurizedfluid-carrying passageways is connected to a pressure responsive linkingmeans having a length which may be increased or decreased depending uponthe pressure exerted on said linking means by a fluid carried by saidpressurized fluid carrying passageways.

1. A pressure sensing valve comprising a valve housing, a pressuresensing means carried within said housing, a porous valve meansresponsive to said pressure sensing means and a series of portsconnected to fluid carrying passageways bored within said housing, saidports being exposed or covered by said valve means as pressure changesare sensed by said pressure sensing sending means.
 2. The valving deviceof claim 1 wherein the valve means comprises a porous piston slidablycarried within said housing.
 3. The valve device of claim 2 wherein saidpiston is continually urged towards and in contact with said pressuresensing means.
 4. The valving device of claim 3 wherein said porouspiston is continuously urged toward said pressure sensing means by aspring biasing means.
 5. The valving device of claim 1 wherein thepressure sensing means includes a pair of pressure chambers separated bya flexible diaphragm.
 6. The valving device of claim 5 wherein one ofsaid pressure chambers is maintained at ambient pressure.
 7. The valvingdevice of claim 5 wherein said pressure chamber is maintained at ambientpressure and the other pressure chamber is adapted to accept pressuresgreater than ambient.
 8. The valving device of claim 1 wherein saidvalve means comprises a porous piston slidably carried within saidhousing and said sensing means includes a pair of pressure chambersseparated by a flexible diaphragm.
 9. The valving device of claim 8wherein said porous piston is being continually urged against saiddiaphragm by a spring biasiNg means.
 10. The valving device of claim 9wherein said porous piston has an intermediate cross sectional area lessthan the cross sectional area of each of its ends.
 11. The valvingdevice of claim 8 wherein the compression of said spring biasing meansis capable of being varied by an adjustable means.
 12. The valvingdevice of claim 1 wherein one of said pressurized fluid-carryingpassageways is connected to a pressure responsive linking means having alength which may be increased or decreased depending upon the pressureexerted on said linking means by a fluid carried by said pressurizedfluid carrying passageways.